/Engine/Source/Runtime/Slate/Public/Framework/Application/SlateUser.h
void StartDragDetection ( const [FWidgetPath](API\Runtime\SlateCore\Layout\FWidgetPath) & PathToWidget, int32 PointerIndex, [FKey](API\Runtime\InputCore\FKey) DragButton, [UE::Slate::FDeprecateVector2DParameter](API\Runtime\SlateCore\Types\FDeprecateVector2DParameter) StartLocation )